One of factors causing noise from a pneumatic tire is the cavity resonance sound phenomenon due to the vibration of the air filled inside the tire. The cavity resonance sound phenomenon refers to a resonance phenomenon occurring inside the tire where a tread surface of a rotating tire contacts an uneven road surface during the rotation and vibrates to cause an internal air vibration. For example, with regard to a general pneumatic tire for a passenger vehicle, the cavity resonance sound having a frequency of 200 Hz-270 Hz is a harsh sound as an interior noise of the vehicle.
A technology of absorbing the cavity resonance sound (sound absorbing) by placing a sound absorbing material inside the tire has been proposed in order to reduce the sound generated by the cavity resonance sound phenomenon (hereinafter referred to as “cavity resonance sound”). For example, it is well known as an effective measure that short fibers having sound absorbing properties are bonded onto the inner surface of the tire with an electrostatic flocking (see Patent Literature 1).
Meanwhile, it is known as a method for repairing a punctured tire to use a puncture repair liquid containing a puncture sealant. In this method, the puncture repair liquid is injected inside the tire from a valve of a wheel, and the injected puncture repair liquid is then circumferentially spread over an inner surface of the tire by rotating the tire. Once the puncture sealant reaches the punctured portion and is cured, the repair of the tire is completed.